Prevalence of Arcobacter spp. in raw ground pork from several geographical regions according to various isolation methods

Studies show that the pathogen Arcobacter is present in beef, poultry, and pork. Several methods have been reported for the isolation of this organism, but none has been adopted as the standard. This has limited the significance of field comparison studies. In the present study, we compared the efficiencies of four Arcobacter isolation methods using raw ground pork collected from slaughter facilities across the United States. We also evaluated the effect of meat fat level and age of animals on the prevalence of Arcobacter in ground pork. The methods chosen for comparison of isolation efficiency were those of Collins, a modified version of the Collins method (Direct Collins), deBoer, and Johnson Murano (JM). These were chosen based on published reports in which they were used to detect Arcobacter in pork products. The JM method was found to be the most successful in consistently detecting Arcobacter, isolating it in 64 of 200 pork samples compared with the Direct Collins method, which isolated Arcobacter in 52 of 200 of those same samples. The Collins method and the deBoer method found Arcobacter present in only a fraction of the samples. The level of contamination was found to vary among the plants, ranging from 0% to 68% prevalence, with 32% overall for all four plants tested. Additionally, ground pork low in fat had a higher contamination frequency (20%) when compared with high-fat pork (4%). Results also showed that meat from younger animals was more frequently contaminated than that from older animals.     

Crystal structures of substrate and substrate analog complexes of protocatechuate 3,4-dioxygenase: endogenous Fe3+ ligand displacement in response to substrate binding

Protocatechuate 3,4-dioxygenase (3,4-PCD) utilizes a ferric ion to catalyze the aromatic ring cleavage of 3,4-dihydroxybenzoate (PCA) by incorporation of both atoms of dioxygen to yield beta-carboxy-cis, cis-muconate. The crystal structures of the anaerobic 3,4-PCD.PCA complex, aerobic complexes with two heterocyclic PCA analogs, 2-hydroxyisonicotinic acid N-oxide (INO) and 6-hydroxynicotinic acid N-oxide (NNO), and ternary complexes of 3,4-PCD.INO.CN and 3,4-PCD. NNO.CN have been determined at 2.1-2.2 A resolution and refined to R-factors between 0.165 and 0.184. PCA, INO, and NNO form very similar, asymmetrically chelated complexes with the active site Fe3+ that result in dissociation of the endogenous axial tyrosinate Fe3+ ligand, Tyr447 (147beta). After its release from the iron, Tyr447 is stabilized by hydrogen bonding to Tyr16 (16alpha) and Asp413 (113beta) and forms the top of a small cavity adjacent to the C3-C4 bond of PCA. The equatorial Fe3+ coordination site within this cavity is unoccupied in the anaerobic 3,4-PCD.PCA complex but coordinates a solvent molecule in the 3,4-PCD.INO and 3,4-PCD.NNO complexes and CN- in the 3,4-PCD.INO.CN and 3,4-PCD.NNO.CN complexes. This shows that an O2 analog can occupy the cavity and suggests that electrophilic O2 attack on PCA is initiated from this site. Both the dissociation of the endogenous Tyr447 and the expansion of the iron coordination sphere are novel features of the 3,4-PCD. substrate complex which appear to play essential roles in the activation of substrate for O2 attack. Together, the structures presented here and in the preceding paper [Orville, A. M., Elango, N. , Lipscomb, J. D., & Ohlendorf, D. H. (1997) Biochemistry 36, 10039-10051] provide atomic models for several steps in the reaction cycle of 3,4-PCD and related Fe3+-containing dioxygenases.     

Structures of competitive inhibitor complexes of protocatechuate 3,4-dioxygenase: multiple exogenous ligand binding orientations within the active site

Protocatechuate 3,4-dioxygenase (3,4-PCD) catalyzes the oxidative ring cleavage of 3,4-dihydroxybenzoate to produce beta-carboxy-cis, cis-muconate. Crystal structures of Pseudomonas putida3,4-PCD [quaternary structure of (alphabetaFe3+)12] complexed with seven competitive inhibitors [3-hydroxyphenylacetate (MHP), 4-hydroxyphenylacetate (PHP), 3-hydroxybenzoate (MHB), 4-hydroxybenzoate (PHB), 3-fluoro-4-hydroxybenzoate (FHB), 3-chloro-4-hydroxybenzoate (CHB), and 3-iodo-4-hydroxybenzoate (IHB)] are reported at 2.0-2.2 A resolution with R-factors of 0. 0.159-0.179. The inhibitors bind in a narrow active site crevasse lined with residues that provide a microenvironment that closely matches the chemical characteristics of the inhibitors. This results in as little as 20% solvent-exposed surface area for the higher-affinity inhibitors (PHB, CHB, and FHB). In uncomplexed 3,4-PCD, the active site Fe3+ is bound at the bottom of the active site crevasse by four endogenous ligands and a solvent molecule (Wat827). The orientations of the endogenous ligands are relatively unperturbed in each inhibitor complex, but the inhibitors themselves bind to or near the iron in a range of positions, all of which perturb the position of Wat827. The three lowest-affinity inhibitors (MHP, PHP, and IHB) yield distorted trigonal bipyramidal iron coordination geometry in which the inhibitor C4-phenolate group displaces the solvent ligand. MHB binds within the active site, but neither its C3-OH group nor the solvent molecule binds to the iron. The C4-phenolate group of the three highest-affinity inhibitors (PHB, CHB, and FHB) coordinates the Fe3+ adjacent to Wat827, resulting in a shift in its position to yield a six-coordinate distorted octahedral geometry. The range of inhibitor orientations may mimic the mechanistically significant stages of substrate binding to 3, 4-PCD. The structure of the final substrate complex is reported in the following paper [Orville, A. M., Lipscomb, J. D., & Ohlendorf, D. H. (1997) Biochemistry 36, 10052-10066].     

Teilautomatisiertes preforming zur Qualitätssicherung und Verkürzung von Fertigungszeiten bei der Herstellung von Rotorblättern von Windenergieanlagen

Quality management and reduction of processing time through automised preforming in the rotorblade manufacturing for wind turbines Rotor blades of wind turbines are mainly manufactured from fibre reinforced plastics. These materials show an excellent performance concering the ratio of stiffness and weight. Basically the composite material of rotor blades is made out of glass fibres and thermosetting material. But growing technological and economical requirements to rotor blades by off‐shore‐application, in particular through increasing rotor blade diameter, have to meet successful. Although reduction of processing time and increased quality of rotor blades play a major role. To achieve the increasing requirements of the rotor blade manufacturing the Bremen Institute for Engineering Design and the rotor blade manufacturer Abeking & Rasmussen Rotec GmbH are working together on the handling and manufacturing of textile preforms. Preforms are made out of stacked and bonded dry textile layers and deposited in the mould as one textile part. Preforming allows the parallel processing of some manufacturing steps. This shows great advantages in the production of fibre reinforced plastics because of the long curing time of the resin component. This parallel processing is required to reach the aim of decreased overall cycle time. This essay is focussing on the handling of textiles and the textile preforming. Summarised aspects of quality management and economics in textile preforming will be discussed with the aim of automising the preforming process.     

Structures of five mutants of toxic shock syndrome toxin-1 with reduced biological activity

The three-dimensional structures of five mutants of toxic shock syndrome toxin-1 (TSST-1) have been determined. These mutations are in the long central alpha helix and are useful in mapping portions of TSST-1 involved in superantigenicity and lethality. The T128A, H135A, Q139K, and I140T mutations appear to reduce superantigenicity by altering the properties of the T-cell receptor interaction surface. The Q136A mutation is at a largely buried site and causes a dramatic change in the conformation of the beta7-beta9 loop which covers the back of the central alpha helix. As this mutation has the unique ability to reduce the toxin's lethality in rabbits while retaining its superantigenicity, it raises the possibility that this rear loop mediates the ability of TSST-1 to induce lethality and suggests a route for producing nonlethal toxins for therapeutic development.     

Sensitivity of three methods used in the isolation of Arcobacter spp. in raw ground pork

Arcobacter, an aerotolerant Campylobacter-like organism, has been designated an emerging pathogen because of its newly recognized ability to cause diarrheal illness in both humans and animals and its presence in the human food supply. Because there is no standard isolation method for its detection, the true occurrence of this pathogen is largely unknown. In addition, the lack of a standardized isolation protocol limits the ability of investigators to compare field data. Arcobacter has been detected in whole muscle and ground pork at various levels by two different isolation methods (those of deBoer and Collins). In this study, these methods were tested along with the Johnson-Murano (JM) method, developed in our laboratory. The sensitivity of each method was tested for ground pork inoculated with Arcobacter butzleri and Arcobacter cryaerophilus IA at levels of 10(4), 10(3), 10(2), and 10(1) CFU/g. Controls included tubes with uninoculated pork and broth tubes without pork. All samples that were morphologically similar to Arcobacter were analyzed by Gram staining and by catalase and oxidasereactions. Presumptive positive samples were confirmed by the polymerase chain reaction. The JM method was determined to be the most sensitive, detecting A. butzleri down to a level of 10(1) CFU/g in 100% of the samples and detecting A. cryaerophilus IA at a level of 10(1) CFU/g in 75% of samples. In a pure buffer system, the Collins method was as effective as the JM method in isolating both organisms to levels of 10(1) cells per g.     

Resonance Raman studies of the protocatechuate 3,4-dioxygenase from Brevibacterium fuscum

Resonance Raman studies of the protocatechuate 3,4-dioxygenase (PCD) from Brevibacterium fuscum have been carried out to take advantage of the high iron-site homogeneity of this enzyme. Native uncomplexed PCD exhibits individual resonance-enhanced nu CO and delta CH vibrations for the two tyrosinates coordinated to the active site iron center, which can be assigned to a particular residue by their excitation profiles. Of the two nu CO features observed at 1254 and 1266 cm-1, only the latter is upshifted (to 1272 cm-1) when H2O is replaced by D2O. Similarly the 1254-cm-1 feature is unaffected, while the 1266-cm-1 feature is shifted to approximately 1290 cm-1 when inhibitors such as phenolates or terephthalate bind to the active site. These observed shifts can be rationalized by the presence of hydrogen-bonding interactions with solvent in the active site cavity, which are modulated by D2O and eliminated upon inhibitor binding. Examination of the PCD crystal structure suggests that the axial tyrosine can be hydrogen bonded in the uncomplexed enzyme to water molecules present in the substrate binding pocket. The equatorial tyrosine may also be hydrogen bonded but to solvent molecules which are trapped in a pocket inaccessible to bulk solvent. These studies allow for the first time the association of particular Raman spectroscopic features, i.e., the nu CO's at 1254 and 1266 cm-1, with the equatorial and axial tyrosine residues in the PCD active site, respectively; they lay the groundwork for further Raman studies on catalytically important species to determine the roles these tyrosine residues may play in the PCD reaction cycle.     

Multicriteria fractional programming — an approach by means of conjugate functions

This paper deals with multicriteria fractional problems. Since this problems in general are not convex, the basic problem will be transformed into a convex optimization problem by using an extension of the conception of Dinkelbach to vector optimization. It will be formulated a dual problem to the transformed optimization problem, where conjugate functions are used. There will be proved strong and converse duality theorems with conclusions to basic fractional problem.     

Phenylnannolones A–C: Biosynthesis of New Secondary Metabolites from the Myxobacterium Nannocystis exedens

Myxobacteria are gliding bacteria that belong to the δ‐Proteobacteria and are known for their unique biosynthetic capabilities. Among myxobacteria, Nannocystis spp. are most closely related to marine myxobacteria and their secondary metabolism has hardly been investigated. Phenylnannolones A ( 1 ), B ( 2 ) and C ( 3 ) were obtained from a culture of Nannocystis exedens that was isolated from the intertidal region of Crete. Compound 1 had inhibitory activity toward the ABCB1 gene product P‐glycoprotein and reversed daunorubicin resistance in cultured cancer cells. Phenylnannolone A has an unusual structural architecture; it is composed of an ethyl‐substituted polyene chain linked to a pyrone moiety on one side and to a phenyl ring on the other. The investigation of the biosynthesis with labelled precursors revealed acetate, butyrate and phenylalanine as building blocks for 1 . The labelling pattern suggested novel biochemical reactions for the biosynthesis of the starter unit.     

Disability glare in soft multifocal contact lenses

Purpose

The study investigated the effect of the design of multifocal contact lenses on the sensitivity to contrast and disability glare.